Method of tube manufacture



Jupe 1l, 1929. E. s. WHnTrli-:R 1,716,608

METHOD OF TUBE MANUFACTURE Filed Nov. 2'?, 1926 j i Z I INVENToR.

Patented `lune 11, 1929.

narran `STATES `Farrar oFFIcE..

ELMER S. IVHTTTIER, OF SPRINGFIELD, MASSACHUSETTS,ASSIGNOR TO THE FISK RUBBER COMPANY, OF CHIGOPEE FALLS, MASSACHUSETTS, A CORPORATION OF! MASSACHUSETTS.

METHOD or 'enen MANFACTURE.

'Application filed November 27, 1926. Serial No. 151,029.

around the valve padV during the rolling of` the tube about the mandrel upon which it is made.

It is customary to make inner tubes by Wrapping rubber stock about a mandrel and then vulcanizing the rubber While so Wrapped upon the mandrel. In order that the tube may be reinforced at that portion through which the valve is to be positioned,

.it is necessary to provide a pad comprising several plies of rubberized fabric. This pad becomes incorporated with the tube during' vulcaniaation andbecomes a part thereof. I-Ieretofore, many tubes have been spoiled because of air or gas being trapped about the edges of the 'valve pad, the heat created during the vulcanization causing this air or gas to expand, and this in turn causing open `seams around the edge of the pad and along` the length of the tube. It is also customary in the manufacture of inner tubes, to use a pair of paper transfers for marking the tubes, one transfer used for the name and size of the tube,fand the other transfer, a

smaller one, for the seria-l number of the tube. It is the purpose of my invention to '55 use one or the other or both of the transfers e to eliminate the open seams in tubes.

` My invention calls for but a slight departure from the usual practise in building tubes, but, although slight, it removes a vserious defect found in theformer practise. My invention Will be described with reference to the accompanying drawings; in which,

1 is a plan vieW, partly broken away, indicating the tube parts just prior to being rolled about a tube forming mandrel;

Fig. 2 is a perspective view of the rubber stock made up of two laminated sheets of material Fig. 3 is a cross-section taken through the line 3 3 of F ig. 1, showing in detail a valve pad and a transfer;

4; a similar tu 3 after rig. 5.'

approximately one revolution of the stoclr about the mandrel;

Fig. 5 is a plan view of a valve pad.;

Fig. 6 is an enlarged cross-sectionV of a valve pad and tube on a mandrel during they vulcanization of the pad and tube; and

-Fig 7 is a modification.

In carrying out my invention, a usual rubber sheet 10, preferably made up of tWo thin laminated sheets, is rolled about a mandrel 11 two or more times. A valvepad a is placed a kshort distance back from the front edge of thefmateria'l 10. Although this pad a. may made in a varied number of forms, the preferred form is shown in Fig. 5, Where a number of layers of fabric 12 are laid in pyramid form upon a thin piece of rubber tube stock 13. Although Fig. 5 for clearness in illustration shows the pad with the layers of fabric uppermost,

the pad a. should be placed in such a manner on the tube material so that the piece of tube stock 13 is uppermost, the layers of fabric 12 lying` between this tube stock 13 and the material 10.` Upon the vulcanization' of the tube, the tube stock 13 will blend perfectly With the tube material 10.

In markinga tube With the name of the manufacturer, size of the tube, etc., it is customary to use a paper transfer 14 that will leave the desired marking on the tube. Another transfer 15 is usually added to supply the serial number of the tube and'is ordinarily placed alongside the larger transfer 1lias shown in Fig. 1. However, as the exact location of the transfers is not important, I prefer to pla-ce the large transfer 14 over the valve pad a as shown in Figs. 1, 3, and 1, and indicated by the dotted lines in One end of the transfer lies over the pad a far enough from the center of the pad so as to be out of the Way of the hole that is later punched through the center of the pad and tube for the insertion of the valve. Although I have shown the transfer 14 lying parallel to the edge of the material, it may be placed at any angle from the pad a., this angle depending on how the tube marking is desired. The principal reason for locating the transfer as shown Will now be explained.

After locating'the pad a and the transfers 14.- andl upon the sheet of material 10, the mandrel 11 is placed along' the edge of the material shown in Figs. l and 3 and rolled, thereby Wrapping the rubber' about it, Fig. l showing an intermediate step. Duringl the rolling, pockets 1G are formed by the stepped-olf edges of the layers of fabric l2 because of insullicient pressure around the valve pad, these pockets holdingair which, if not removed, will cause open seams as described.

The trapped air will remain in the pockets 1G until the -milcanization of the 'tube before which, however, the ends of the tube are tightly sealed to the mandrel by a cuff, by being Wrapped, or by any other method. The heat of the subsequent vulcanization Will cause the trapped air to expand, this air, due to the vu'lcanizing pres.,.ure, being' ,forced along the cords of the fabric layers 'l2 of the Valve pad ai into a recess l? cut through the tube material 13 and through one or more layers of fabric l2 of the pad a. The continually expandina` air will tend to force the pad (t away from the mandrel. 1l and forni a recess 18 6). Not adhering to the mandrel as much as the tacky rubber stoclc10,-the transfer 1l will allimr the air to pocket itself between the saidl transfer and the mandrel lll. This diffuses the air from a comparatively small area about the pad a. over a large area formed between the transfer' lll and the mandrel ll. The diffusion of the air reduces the imensity of its effect, and the injurious effect of its presence under the paper ltransfer is much less than the presence of an equiralent amount under a similar area of rubber.

Although the above disclosure is my preferred method, ll can also use the smaller transfer to accomplish the same purpose in practically the same manner. Here l place the larger transfer 14; .imc part of the material other than over the pad a and locate the smaller transfer l5 so that one end comes to approximately the center of the pad while the other end lies between the edges 19 and 2O of thevlaminated sheets of material 10 (Fior 7). ln this case,.the cX- panding air from about the pad a will seep out through the Vent formed by the transfer 15 into the seam 2l from which it is diffused. The trapped air about the pad, if not drawn i claim l. A method of making a rubber tube of the type having a fabric laminated valve pad embedded in the rubber tube n'iaterial, which consists in venl g the valve pad to a point remote from the pad, and vulcanizing` the pad and tube together.

2. A method of mana'hicturing` an inner tube for tire casings which consists in placingv a Valve pad on rubber tule material, loeating a rpaper transfer strip partially across the Valve pad, rolling the whole about a mandrel, and wilcanizing` the pad and tube together.

3. A method of making a rolled rubber tube of the type haring a fabric laminated Valve pad embedded in the rubber tubeniaterial, which consists in venting the ralre pad into the longitudinal seam formed by y the rolling' of the tube, and vulcanizing` the pad and tube together.

A method of manufacturing an inner tube for tire easings Which consists in locat ing` a valve pad on rubber tube material, locating a paper transfer strip across the ralve pad toward the edge of the/tube material, rolling the Whole about a mandrel, and rulcanizing the pad and tube together.

5. A. method of manufacttiring` an inner tube for tire casingsvwhich consistfl in placing` a valve pad on rubber tube material, locating; a. paper t 'ansfer strip partially across the Valve pad to form a pocliet, locating another transfer strip across the Valve pad toward the edge of the tube ma'erial to form a. vent into the longittulinal seam formed by the rolling; of the tube, rolling the Whole about ,a mandrel, and vulcani'/ ing the pad and tube together. 

